Not knowing where to start in deciding what career you want is very common and normal. There are a number of starting points and these will be different for different people. Choosing a career is not a once off process. One develops ideas in a series of steps. Careers are constructed over time, not chosen as a once off decision.
Have a look at what you need to do at each stage of your time at UCT:
Download Plan Your Journey: First Years map here
Download Plan Your Journey: Intermediate Years map here
Download Plan Your Journey: Final Year map here